Fluid ejection device and medical device

ABSTRACT

A fluid ejection device includes: a pressure chamber; an actuator having a displacement plane that varies the volume of the pressure chamber; a delivery channel pipe communicating with the pressure chamber; a first reflection surface of pressure wave formed as part of a paraboloid of revolution that reflects a plane pressure wave by displacement of the actuator, the plane pressure wave propagating through the pressure chamber; and a second reflection surface of pressure wave formed as part of a paraboloid of revolution or an ellipsoid of revolution which is disposed so as to face the first reflection surface of pressure wave, wherein the first reflection surface of pressure wave and the second reflection surface of pressure wave have a common first focus, and a pressure wave reflected from the second reflection surface of pressure wave propagates through the delivery channel pipe and ejects fluid.

This application is a continuation of U.S. patent application Ser. No.13/268,034, filed Oct. 7, 2011, which claims priority to Japanese PatentApplication No. 2010-228178, filed on Oct. 8, 2010, and Japanese PatentApplication No. 2011-148896, filed on Jul. 5, 2011 the entirety of whichare hereby incorporated by reference.

BACKGROUND

1. Technical Field

The present invention relates to fluid ejection devices and medicaldevices using the fluid ejection device.

2. Related Art

In the past, a fluid ejection device that converts fluid into ahigh-pressure pulsating current by varying the volume of a pressurechamber with a volume varying unit formed of a diaphragm and apiezoelectric element and pulsatively ejects the fluid at high velocityout of a nozzle by propagating a pressure wave through a deliverychannel pipe from the pressure chamber has been proposed (see, forexample, JP-A-2008-82202 (Patent Document 1)).

Moreover, a nozzleless inkjet fluid ejection device that ejects ink byforming, in the bottom of an ink chamber filled with ink, a paraboloidalreflecting plate from which acoustic energy is reflected, exciting apiezoelectric element provided on the ink surface, reflecting acousticenergy by the reflecting plate, and exciting the ink surface byconcentrating the acoustic energy onto the focus of the paraboloid hasbeen proposed (see, for example, JP-A-2-95857 (Patent Document 2)).

In the fluid ejection device structured as in Patent Document 1, a planepressure wave generated in the pressure chamber by the driving of thepiezoelectric element propagates through the pressure chamber and thedelivery channel pipe communicating with the pressure chamber, thedelivery channel pipe having a channel whose diameter is smaller thanthat of the pressure chamber. At this time, most of the plane pressurewave is reflected off an inner wall that surrounds the delivery channelpipe, the inner wall facing the piezoelectric element. Therefore, it isimpossible to transfer the energy of the plane pressure wave to theinside of the delivery channel pipe efficiently.

On the other hand, it was believed that, in the structure as describedin Patent Document 2, since the acoustic energy (incidentally, theacoustic energy can be replaced with the energy of the pressure wave)generated by the piezoelectric actuator was reflected from thereflecting plate and was converged onto the focus of the paraboloidlocated near the surface of the ink, the energy of the pressure wavecould be concentrated onto the ink surface efficiently. However, sincethe acoustic energy which has been made to converge on the focus passesthrough the focus and then spreads radially because the focus of theparaboloid is provided in an ink ejection port, the ejected ink dropletsometimes breaks up, making it impossible to use the acoustic energyefficiently for ejecting the ink.

SUMMARY

An advantage of some aspects of the invention is to solve at least partof the problems described above, and the invention can be realized asforms or application examples described below.

APPLICATION EXAMPLE 1

A fluid ejection device according to this application example includes:a pressure chamber; an actuator having a displacement plane that variesthe volume of the pressure chamber; a delivery channel pipecommunicating with the pressure chamber; a first reflection surface ofpressure wave formed as part of a paraboloid of revolution that reflectsa plane pressure wave by displacement of the actuator, the planepressure wave propagating through the pressure chamber; and a secondreflection surface of pressure wave formed as part of a paraboloid ofrevolution or an ellipsoid of revolution which is disposed so as to facethe first reflection surface of pressure wave, wherein the firstreflection surface of pressure wave and the second reflection surface ofpressure wave have a common first focus, and a pressure wave reflectedfrom the second reflection surface of pressure wave propagates throughthe delivery channel pipe and ejects fluid.

Here, the paraboloid of revolution is a plane formed by revolving aparabola 360 degrees about the symmetry axis thereof, and a central axisof rotation corresponds to the symmetry axis described above.

Here, the ellipsoid of revolution is a plane formed by revolving anellipse 360 degrees about the major axis thereof, and a central axis ofrotation corresponds to the major axis described above.

According to this application example, by driving the actuator, theplane pressure wave generated by the displacement plane of the actuatoris made to converge on the first focus by the first reflection surfaceof pressure wave. The pressure wave which has converged propagates whilespreading radially in the pressure chamber, is then reflected from thesecond reflection surface of pressure wave, and propagates through thedelivery channel pipe. This makes it possible to transfer the pressurewave efficiently to the inside of the delivery channel pipe and use theenergy of the pressure wave generated by the actuator for fluid ejectionwith high efficiency.

Incidentally, a common first focus in “the first reflection surface ofpressure wave and the second reflection surface of pressure wave have acommon first focus” in this application example means that there is nodifference between the focus positions or there is a difference betweenthe focus positions within the allowable range. The allowable range iswithin 10% of the distance between a point of intersection of theparaboloid of revolution or the ellipsoid of revolution including thesecond reflection surface of pressure wave and the central axis ofrotation thereof and the first focus of the second reflection surface ofpressure wave, in which it is expected that the effects of the inventionwill be obtained. Preferably, the allowable range is within 5% of theabove distance, and, ideally, 0%, that is, there is no differencebetween the focus positions.

APPLICATION EXAMPLE 2

In the fluid ejection device according to the application exampledescribed above, it is preferable that a central axis of rotation of thefirst reflection surface of pressure wave and a central axis of rotationof the second reflection surface of pressure wave be nearly parallel toeach other.

In such a configuration, the central axes of rotation are disposed so asto be nearly parallel to each other. Therefore, the component elementshave good symmetries, making it possible to make the plane pressure wavegenerated by the actuator propagate through the delivery channel pipeefficiently by the first reflection surface of pressure wave and thesecond reflection surface of pressure wave.

Incidentally, with such a configuration, it is possible to dispose theactuator, the pressure chamber, the first reflection surface of pressurewave, the second reflection surface of pressure wave, and the deliverychannel pipe in a linear arrangement. This simplifies the structure andmakes production easier.

Incidentally, the central axes of rotation which are nearly parallelmean that the central axes of rotation are parallel to each other orintersect within the allowable crossing angle range. The allowablecrossing angle range is within ±5° in which it is expected that theeffects of the invention will be obtained. Preferably, the allowablecrossing angle range is within ±2.5°, and, ideally, 0°, that is, thecentral axes of rotation are parallel to each other (the same holds truefor the following description).

APPLICATION EXAMPLE 3

In the fluid ejection device according to the application exampledescribed above, it is preferable that the central axis of rotation ofthe first reflection surface of pressure wave and the central axis ofrotation of the second reflection surface of pressure wave coincide witheach other.

In such a configuration, the central axes of rotation are made tocoincide with each other. Therefore, the component elements have goodsymmetries, making it possible to make the plane pressure wave generatedby the actuator propagate through the delivery channel pipe moreefficiently by the first reflection surface of pressure wave and thesecond reflection surface of pressure wave.

Incidentally, the central axes of rotation coinciding with each othermean that the central axes of rotation are nearly parallel to each otherand there is no difference in positions of the central axes of rotationin a direction perpendicular to the central axes of rotation or there isa difference in positions of the central axes of rotation in a directionperpendicular to the central axes of rotation within the allowablerange. The allowable range is within 10% of the distance between a pointof intersection of the paraboloid of revolution or the ellipsoid ofrevolution including the second reflection surface of pressure wave andthe central axis of rotation thereof and the first focus of the secondreflection surface of pressure wave, in which it is expected that theeffects of the invention will be obtained. Preferably, the allowablerange is within 5% of the above distance, and, ideally, 0%, that is,there is no difference in positions of the central axes of rotation in adirection perpendicular to the central axes of rotation (the same holdstrue for the following description).

APPLICATION EXAMPLE 4

In the fluid ejection device according to the application exampledescribed above, it is preferable that a central axis of rotation of thefirst reflection surface of pressure wave and a central axis of rotationof the second reflection surface of pressure wave be not parallel toeach other.

With such a configuration, it is possible to make the pressure wavereflected from the second reflection surface of pressure wave propagatein a direction inclined to a direction in which the plane pressure wavegenerated by the actuator propagates. Thus, by making the central axisof the delivery channel pipe nearly parallel to the direction in whichthe pressure wave propagates, it is possible to realize a configurationof the fluid ejection device having the delivery channel pipe in adirection off the central axis of the displacement plane of the actuatorand make the plane pressure wave generated by the actuator propagatethrough the pressure chamber and the delivery channel pipe efficiently.

APPLICATION EXAMPLE 5

In the fluid ejection device according to the application exampledescribed above, it is preferable that a central axis of thedisplacement plane of the actuator and a central axis of rotation of thefirst reflection surface of pressure wave be nearly parallel to eachother, and a central axis of the delivery channel pipe and a centralaxis of rotation of the second reflection surface of pressure wave benearly parallel to each other.

In such a configuration, the central axis of rotation and the centralaxis of the displacement plane are made to be nearly parallel to eachother, and the central axis of rotation and the central axis of thedelivery channel pipe are made to be nearly parallel to each other.Therefore, the component elements have good symmetries, making itpossible to make the plane pressure wave generated by the actuatorpropagate through the delivery channel pipe efficiently by the firstreflection surface of pressure wave and the second reflection surface ofpressure wave.

Incidentally, with such a configuration, it is possible to dispose theactuator, the first reflection surface of pressure wave, the secondreflection surface of pressure wave, and the delivery channel pipe in alinear arrangement. This simplifies the structure and makes productioneasier.

APPLICATION EXAMPLE 6

In the fluid ejection device according to the application exampledescribed above, it is preferable that the central axis of thedisplacement plane of the actuator and the central axis of rotation ofthe first reflection surface of pressure wave coincide with each other,and the central axis of the delivery channel pipe and the central axisof rotation of the second reflection surface of pressure wave coincidewith each other.

In such a configuration, the central axis of rotation and the centralaxis of the displacement plane are made to coincide with each other, andthe central axis of rotation and the central axis of the deliverychannel pipe are made to coincide with each other. Therefore, thecomponent elements have even better symmetries, making it possible tomake the plane pressure wave generated by the actuator propagate throughthe delivery channel pipe more efficiently by the first reflectionsurface of pressure wave and the second reflection surface of pressurewave.

APPLICATION EXAMPLE 7

In the fluid ejection device according to the application exampledescribed above, it is preferable that the central axis of thedisplacement plane of the actuator and the central axis of rotation ofthe first reflection surface of pressure wave be away from each other,and the central axis of the delivery channel pipe and the central axisof rotation of the second reflection surface of pressure wave be awayfrom each other.

In such a configuration, the axes of the component elements are nearlyparallel to each other and are away from each other. Therefore, thesecond reflection surface of pressure wave can reflect the pressure waveto a position which is nearly parallel to the plane pressure wavegenerated by the actuator, the position away from the plane pressurewave generated by the actuator, and make the pressure wave propagatethrough the delivery channel pipe which is also nearly parallel to thecentral axis of the displacement plane of the actuator and is awaytherefrom. This makes it possible to increase configuration flexibilityof the fluid ejection device and transfer the pressure wave efficientlyto the inside of the delivery channel pipe.

APPLICATION EXAMPLE 8

In the fluid ejection device according to the application exampledescribed above, it is preferable that a second focus of the ellipsoidof revolution of the second reflection surface of pressure wave bedisposed inside the delivery channel pipe.

In such a configuration, the pressure wave reflected from the secondreflection surface of pressure wave converges on the second focus andspreads in the delivery channel pipe. Since the second focus is locatedinside the delivery channel pipe, the pressure wave spreading from thesecond focus propagates while being reflected from the inner wall of thedelivery channel pipe. Also with such a configuration, it is possible tomake the plane pressure wave generated by the actuator propagate throughthe pressure chamber and the delivery channel pipe efficiently.

APPLICATION EXAMPLE 9

A medical device according to this application example employs the fluidejection device described in any one of the application examplesdescribed above.

The medical device according to this application example can convertliquid into pulsed minuscule droplets and eject them at high velocity,and has excellent properties as a surgical instrument, such as causingno thermal damage when excising, incising, or crushing a living tissueand being capable of preserving a tubule tissue such as a blood vessel.Moreover, another advantage is that, when operations etc. are conductedby using the fluid ejection device described above, the amount ofejected liquid is small as compared to an existing device using ahigh-pressure flow, making it easy to see an operative site.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a sectional view showing the structure of a fluid ejectiondevice according to a first embodiment.

FIGS. 2A to 2D are voltage waveform diagrams driving an actuatoraccording to the first embodiment.

FIG. 3 is an explanatory diagram showing the propagation of a pressurewave according to the first embodiment.

FIG. 4 is an explanatory diagram showing the propagation of a pressurewave according to a second embodiment.

FIG. 5 is a sectional view showing the structure of a fluid ejectiondevice according to a third embodiment.

FIG. 6 is an explanatory diagram showing the propagation of a pressurewave according to the third embodiment.

FIG. 7 is a sectional view showing the structure of a fluid ejectiondevice according to a fourth embodiment and the propagation of apressure wave.

FIG. 8 is a sectional view showing the structure of a fluid ejectiondevice according to a fifth embodiment.

FIG. 9 is an explanatory diagram showing the propagation of a pressurewave according to the fifth embodiment.

FIG. 10 is a sectional view showing the structure of a fluid ejectiondevice according to a sixth embodiment and the propagation of a pressurewave.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the invention will be described based on thedrawings.

Incidentally, for the sake of illustration, the drawings which arereferred to in the following description are schematic diagrams in whichthe shapes and the horizontal and vertical scale ratio of the componentelements or portions are different from those of the actual componentelements or portions, and the component elements or portions are shownin simplified forms to make the description understandable.

First Embodiment

FIG. 1 is a sectional view showing the structure of a fluid ejectiondevice according to this embodiment. In FIG. 1, a fluid ejection device10 includes a pressure generating section 30 having a pressure chamber60 and an actuator 70 as a volume varying unit that varies the volume ofthe pressure chamber 60, a fluid supply pipe 43 having a fluid supplychannel 44 communicating with the pressure chamber 60, and a deliverychannel pipe 51 having a delivery channel 52 communicating with thepressure chamber 60.

The actuator 70 is a ring-shaped piezoelectric element. One end face ofactuator 70 is fixed to an inner bottom face of a first machine casing40, and the other end face is tightly fixed to a diaphragm 80 via areinforcing member (not shown). By the application of a voltage, theother end face 71 (hereinafter referred to as a displacement plane 71)can stretch and shrink in the direction of an arrow A (the thicknessdirection). When the actuator 70 rapidly stretches and shrinks, a planepressure wave is generated via the diaphragm 80. The outer edge of thediaphragm 80 is fixed to the first machine casing 40 or a second machinecasing 50.

Incidentally, the actuator 70 is not limited to the piezoelectricelement, and any element that can vary the volume of the pressurechamber 60 and generate a plane pressure wave can be used as theactuator 70.

In the center of the bottom face of the first machine casing 40, aprojection penetrating the actuator 70 is formed, and, at the tip of theprojection, a paraboloid of revolution is formed. The paraboloid ofrevolution will be referred to as a second reflection surface ofpressure wave M2. Incidentally, the second reflection surface ofpressure wave M2 juts from the displacement plane 71 of the actuator 70.

In FIG. 1, the fluid supply pipe 43 is formed in the second machinecasing 50 so as to project therefrom; however, a structure in which thesecond machine casing 50 and the fluid supply pipe 43 are provided asseparate components and the fluid supply pipe 43 is fixed to the secondmachine casing 50 by being press-fitted thereinto may be adopted. To thefluid supply pipe 43, a pump 20 as an unillustrated fluid supplyingsection is connected, and the pump 20 supplies fluid to the pressurechamber 60 at a constant pressure or a constant flow rate.

Incidentally, the first machine casing 40, the second machine casing 50,the fluid supply pipe 43, the delivery channel pipe 51, and a fluidejection opening 53 are formed of sufficiently hard materials andpossess stiffness which is high enough to prevent those components frombeing deformed by the pressure wave propagating through the fluid.

Moreover, in FIG. 1, in the second machine casing 50, the deliverychannel pipe 51 is provided so as to project therefrom; however, astructure in which the second machine casing 50 and the delivery channelpipe 51 are provided as separate components and the delivery channelpipe 51 is fixed to the second machine casing 50 by being press-fittedthereinto may be adopted. At the tip of the delivery channel pipe 51,the fluid ejection opening 53 (which will be also referred to as anozzle) whose channel diameter has a cross-sectional area which issmaller than the cross-sectional area of the delivery channel 52 isformed.

The first machine casing 40 and the second machine casing 50 are tightlyfixed to each other at the faces at which the first machine casing 40and the second machine casing 50 face each other, and a space surroundedby the inner wall of the second machine casing 50, the displacementplane 71 of the actuator 70, and the second reflection surface ofpressure wave M2 is the pressure chamber 60. In addition, a face facingthe displacement plane 71 and the second reflection surface of pressurewave M2 is a first reflection surface of pressure wave M1 formed as aparaboloid of revolution.

Next, fluid ejection action of the fluid ejection device 10 will bedescribed with reference to FIG. 1. It is to be noted that descriptionwill be given on the assumption that the fluid is liquid. First, a drivewaveform which is applied to drive the actuator 70 will be described.

FIG. 2A shows a fundamental drive voltage waveform diagram driving theactuator 70. As shown in FIG. 2A, the fundamental voltage waveform is avoltage waveform that rises sharply and falls gradually. In a risingregion in which the drive voltage increases sharply, the actuator 70rapidly stretches, and, in a falling region in which the drive voltagedecreases gradually, the actuator 70 returns to its original length.This drive waveform is a fundamental voltage waveform driving theactuator 70.

When the fluid ejection device 10 is actually driven, the fundamentalvoltage waveform may be applied repeatedly with a certain period asshown in FIG. 2B or applied repeatedly for a finite number of times witha certain period as shown in FIG. 2C. Alternatively, as shown in FIG.2D, the fundamental voltage waveform may be applied singly.

To the fluid supply channel 44, liquid is always supplied by the pump 20at a constant pressure (or a constant flow rate). As a result, in astate in which the actuator 70 does not stretch and shrink, that is, ina steady state, the liquid with a constant flow rate that is determinedby the supply pressure of the pump 20 and the channel resistance of theentire channel system extending from the fluid supply channel 44 to thefluid ejection opening 53 via the pressure chamber 60 and the deliverychannel 52 flows from the pump 20 to the fluid ejection opening 53.

Here, suppose that a drive voltage is applied to the actuator 70 and theactuator 70 stretches rapidly. As a result, the volume of the pressurechamber 60 is rapidly reduced, and the pressure increases rapidly due tothe compressibility of the fluid itself in the pressure chamber 60. Thepressure which has been rapidly increased in the pressure chamber 60starts propagating through the delivery channel 52 to the fluid ejectionopening 53 as a pressure wave with an extremely large fluiddisplacement. The pressure wave propagates through the delivery channel52 to the fluid ejection opening 53 at the velocity of sound propagatingthrough the fluid, and is ejected as a high-speed jet when reaching thefluid ejection opening 53. Therefore, to eject a high-speed jet withhigh kinetic energy out of the fluid ejection opening 53, it isimportant to transfer the energy of the pressure wave provided by therapid stretch of the actuator 70 to the fluid ejection opening 53efficiently with the smallest possible loss.

Thus, the propagation of the pressure wave will be described withreference to FIG. 3.

FIG. 3 is an explanatory diagram showing the propagation of the pressurewave according to this embodiment. First, the relationship among thecomponent elements will be described. In FIG. 3, the paraboloid ofrevolution of the first reflection surface of pressure wave M1 and theparaboloid of revolution of the second reflection surface of pressurewave M2 have a focus in common, and this focus is assumed to be a firstfocus F1. The central axes of rotation of the paraboloids of revolutionof the first reflection surface of pressure wave M1 and the secondreflection surface of pressure wave M2, the central axis of thedisplacement plane 71 of the actuator 70, and the central axis of thedelivery channel pipe 51 coincide with each other (which are depicted asa P-axis in the drawing), and the first focus F1 is located on theP-axis. Incidentally, the P-axis is the same as a z-axis of a coordinatesystem.

Next, the shapes of the first reflection surface of pressure wave M1 andthe second reflection surface of pressure wave M2 and the propagation ofthe pressure wave will be described with reference to FIG. 3 by usingthree-dimensional coordinate representation. The plane coordinates whichare parallel to the displacement plane 71 are expressed by an x-axis anda y-axis, an axis perpendicular to the x-y plane is assumed to be az-axis, and the coordinates are expressed as (x, y, z). The origin ofcoordinates P0(0, 0, 0) is assumed to be a point of intersection of thefirst reflection surface of pressure wave M1 and the P-axis, and, whenthe position of the first focus F1 is assumed to be (0, 0, f), theorigin of coordinates P0(0, 0, 0) is assumed to be a vertex of theparaboloid of revolution which is the first reflection surface ofpressure wave M1. Moreover, when the position of the first focus F1 isassumed to be (0, 0, f), the paraboloid of revolution of the firstreflection surface of pressure wave M1 can be expressed by the followingformulae.

$\begin{matrix}{Z = {\frac{1}{4f}\left( {x^{2} + y^{2}} \right)}} & (1) \\{r^{2} \leq {x^{2} + y^{2}} \leq R^{2}} & (2)\end{matrix}$

Moreover, the paraboloid of revolution of the second reflection surfaceof pressure wave M2 can be expressed by the following formulae.

$\begin{matrix}{Z = {{{- \frac{R}{4{fr}}}\left( {x^{2} + y^{2}} \right)} + {f\left( {1 + \frac{r}{R}} \right)}}} & (3) \\{{x^{2} + y^{2}} \leq r^{2}} & (4)\end{matrix}$

Here, r is the radius of the delivery channel 52, and R is theperipheral radius of the actuator 70. However, it is assumed that R>rand f>R/2.

When the pressure chamber 60 is filled with the liquid, if the actuator70 stretches rapidly (in the direction of an arrow A1), a plane pressurewave a1 is generated by the displacement plane 71. The generated planepressure wave a1 propagates to the first reflection surface of pressurewave M1 (in the direction of an arrow a1) in the direction of theP-axis, and is reflected from the first reflection surface of pressurewave M1. The reflected pressure wave a2 propagates in the direction ofan arrow a2, spreads to the second reflection surface of pressure waveM2 after converging on the first focus F1, and is then reflected fromthe second reflection surface of pressure wave M2. Since the first focusF1 is a common focus of the paraboloid of revolution of the firstreflection surface of pressure wave M1 and the paraboloid of revolutionof the second reflection surface of pressure wave M2, the pressure wavea3 reflected from the second reflection surface of pressure wave M2propagates through the delivery channel 52 in the direction of theP-axis (in the direction of an arrow a3).

Incidentally, the shapes and placement of the paraboloid of revolutionof the first reflection surface of pressure wave M1 and the paraboloidof revolution of the second reflection surface of pressure wave M2 areset so that a line segment connecting an edge portion (the outermostedge) of the paraboloid of revolution of the first reflection surface ofpressure wave M1 and the first focus F1 does not intersect with thesecond reflection surface of pressure wave M2. That is, the pressurewave transfer path is set so that the pressure wave reflected from thefirst reflection surface of pressure wave M1 is not blocked by thesecond reflection surface of pressure wave M2 itself.

Therefore, according to this embodiment, the plane pressure wave a1generated by the displacement plane 71 by driving the actuator 70 ismade to converge on the first focus F1 by the first reflection surfaceof pressure wave M1. The pressure wave which has converged propagates inthe pressure chamber 60 while spreading radially, enters the secondreflection surface of pressure wave M2, is reflected from the paraboloidof revolution of the second reflection surface of pressure wave M2, andpropagates through the delivery channel pipe 51 (the delivery channel52). By doing so, it is possible to transfer the pressure waveefficiently to the inside of the delivery channel pipe 51 and use theenergy of the pressure wave generated by the actuator 70 for fluidejection with high efficiency.

Moreover, in this embodiment, the central axes of rotation of the firstreflection surface of pressure wave M1 and the second reflection surfaceof pressure wave M2, the central axis of the displacement plane 71, andthe central axis of the delivery channel pipe 51 are made to coincidewith each other. As a result, the component elements have goodsymmetries, making it possible to make the plane pressure wave generatedby the actuator 70 propagate through the delivery channel pipe 51efficiently by the first reflection surface of pressure wave M1 and thesecond reflection surface of pressure wave M2.

Incidentally, with this structure, it is possible to place the actuator70, the pressure chamber 60, the first reflection surface of pressurewave M1, the second reflection surface of pressure wave M2, and thedelivery channel pipe 51 in a linear arrangement. This simplifies thestructure and makes production easier.

Incidentally, the common first focus F1 of the first reflection surfaceof pressure wave M1 and the second reflection surface of pressure waveM2 in this embodiment means that there is no difference between thefocus positions of the first reflection surface of pressure wave M1 andthe second reflection surface of pressure wave M2 or there is adifference between the focus positions within the allowable range. Theallowable range is within 10% of the distance between a point ofintersection of the second reflection surface of pressure wave M2 andthe P-axis and the first focus F1, in which it is expected that theeffects of this embodiment will be obtained. Preferably, the allowablerange is within 5% of the above distance, and, ideally, 0%, that is,there is no difference between the focus positions of the firstreflection surface of pressure wave M1 and the second reflection surfaceof pressure wave M2.

The evaluation by an experiment has confirmed that the pressure wave isefficiently transferred to the inside of the delivery channel pipe 51when the allowable range is within 10% of the distance between the pointof intersection of the second reflection surface of pressure wave M2 andthe P-axis and the first focus F1 since an angle at which the pressurewave reflected from the second reflection surface of pressure wave M2strikes the wall surface of the delivery channel pipe 51 when passingthrough the delivery channel pipe 51 is kept within an angle ofincidence of 6 degrees as compared to a case in which the allowablerange exceeds 10% and an angle at which the pressure wave reflected fromthe second reflection surface of pressure wave M2 strikes the wallsurface of the delivery channel pipe 51 when passing through thedelivery channel pipe 51 exceeds an angle of incidence of 6 degrees.Moreover, it has been confirmed that the efficiency is expresslyimproved when the allowable range is within 2% of the distance betweenthe point of intersection of the second reflection surface of pressurewave M2 and the P-axis and the first focus F1 (the same holds true forthe following description).

Moreover, the central axes of rotation which are nearly parallel to eachother mean that the central axes of rotation are parallel to each otheror intersect within the allowable crossing angle range. The allowablecrossing angle range is within ±5° in which it is expected that theeffects of this embodiment will be obtained. Preferably, the allowablecrossing angle range is within ±2.5°, and, ideally, 0°, that is, thecentral axes of rotation are parallel to each other (the same holds truefor the following description).

Furthermore, the central axes of rotation coinciding with each othermean that the central axes of rotation are nearly parallel to each otherand there is no difference in positions of the central axes of rotationin a direction perpendicular to the central axes of rotation or there isa difference in positions of the central axes of rotation in a directionperpendicular to the central axes of rotation within the allowablerange. The allowable range is within 10% of the distance between thepoint of intersection of the second reflection surface of pressure waveM2 and the P-axis and the first focus F1, in which it is expected thatthe effects of this embodiment will be obtained. Preferably, theallowable range is within 5% of the above distance, and, ideally, 0%,that is, there is no difference in positions of the central axes ofrotation in a direction perpendicular to the central axes of rotation(the same holds true for the following description). This is the same asthe evaluation by the experiment conducted on the first focus F1.

Second Embodiment

Next, a fluid ejection device according to a second embodiment will bedescribed with reference to the drawing. Unlike the first embodimentdescribed above (see FIG. 3), the features of the second embodiment arethat the second reflection surface of pressure wave M2 is formed as anellipsoid of revolution, and a second focus located on the major axis ofthe ellipsoid of revolution exists inside the delivery channel pipe 51.Therefore, only differences from the first embodiment are explained, andsuch elements as are found also in the first embodiment will beidentified with the same reference characters.

FIG. 4 is an explanatory diagram showing the propagation of a pressurewave according to this embodiment. In FIG. 4, the first reflectionsurface of pressure wave M1 is formed as a paraboloid of revolution, andthe second reflection surface of pressure wave M2 is formed as anellipsoid of revolution. In this embodiment, the central axis of thedisplacement plane 71 of the actuator 70, the central axes of rotationof the first reflection surface of pressure wave M1 and the secondreflection surface of pressure wave M2, and the central axis of thedelivery channel pipe 51 are located on a common axis (a P-axis).

The focus of the paraboloid of revolution of the first reflectionsurface of pressure wave M1 is the same as one of the focuses of theellipsoid of revolution of the second reflection surface of pressurewave M2, and this common focus is referred to as a first focus F1. Inaddition, the ellipsoid of revolution of the second reflection surfaceof pressure wave M2 has a second focus F2 on the major axis thereof in aposition farther away from the ellipsoid of revolution of the secondreflection surface of pressure wave M2 than the first focus F1, and thesecond focus F2 is disposed inside the delivery channel 52.

In such a configuration, when the actuator 70 stretches rapidly (in thedirection of an arrow A1), a plane pressure wave a1 is generated by thedisplacement plane 71, and the generated plane pressure wave a1propagates to the first reflection surface of pressure wave M1 inparallel to the P-axis and is reflected from the first reflectionsurface of pressure wave M1. After converging on the first focus F1, thereflected pressure wave a2 spreads to the second reflection surface ofpressure wave M2, enters the second reflection surface of pressure waveM2, and is then reflected therefrom. After converging on the secondfocus F2, the pressure wave a3 reflected from the second reflectionsurface of pressure wave M2 spreads, reaches the inner wall of thedelivery channel pipe 51, and propagates through the delivery channel 52while being reflected from the inner wall (this reflected pressure waveis shown as a pressure wave a4).

Since the second focus F2 is disposed in the delivery channel pipe 51(the delivery channel 52), the pressure wave a3 propagates through thedelivery channel pipe 51. Therefore, the pressure wave a3 reflected fromthe second reflection surface of pressure wave M2 converges in thedelivery channel pipe 51.

Incidentally, the shapes and placement of the paraboloid of revolutionof the first reflection surface of pressure wave M1 and the ellipsoid ofrevolution of the second reflection surface of pressure wave M2 are setso that a line segment connecting an edge portion (the outermost edge)of the paraboloid of revolution of the first reflection surface ofpressure wave M1 and the first focus F1 does not intersect with thesecond reflection surface of pressure wave M2. That is, the pressurewave transfer path is set so that the pressure wave reflected from thefirst reflection surface of pressure wave M1 is not blocked by thesecond reflection surface of pressure wave M2 itself.

Moreover, the shapes and placement of the paraboloid of revolution ofthe first reflection surface of pressure wave M1 and the ellipsoid ofrevolution of the second reflection surface of pressure wave M2 are setso that a line segment connecting an edge portion (the outermost edge)of the ellipsoid of revolution of the second reflection surface ofpressure wave M2 and the second focus F2 does not intersect with theinner wall surface of the delivery channel pipe 51. That is, thepressure wave transfer path is set so that most of the pressure wavereflected from the second reflection surface of pressure wave M2 entersthe delivery channel pipe 51.

Therefore, according to this embodiment, the pressure wave reflectedfrom the second reflection surface of pressure wave M2 converges on thesecond focus F2 and then spreads in the delivery channel pipe 51. Sincethe second focus F2 is located in the delivery channel pipe 51, thepressure wave spreading from the second focus F2 propagates while beingreflected from the inner wall of the delivery channel pipe 51. Also withsuch a configuration, it is possible to make the plane pressure wavegenerated by the actuator 70 propagate through the delivery channel pipe51 efficiently by the first reflection surface of pressure wave M1 andthe second reflection surface of pressure wave M2.

Third Embodiment

Next, a fluid ejection device according to a third embodiment will bedescribed with reference to the drawings. Unlike the first embodimentdescribed above (see FIG. 3), the features of the third embodiment arethat the central axes of rotation of the paraboloid of revolution of thefirst reflection surface of pressure wave M1 and the paraboloid ofrevolution of the second reflection surface of pressure wave M2 coincidewith each other, the central axis of the delivery channel pipe 51, thecentral axis of the displacement plane 71 of the actuator 70, and thecentral axes of rotation of the paraboloid of revolution of the firstreflection surface of pressure wave M1 and the paraboloid of revolutionof the second reflection surface of pressure wave M2 are nearly parallelto one another and are away from one another. Therefore, onlydifferences from the first embodiment are explained, and such elementsas find their functionally equivalent counterparts in the firstembodiment will be identified with the same reference characters.

FIG. 5 is a sectional view showing the structure of the fluid ejectiondevice according to this embodiment. In FIG. 5, the central axis ofrotation of the paraboloid of revolution of the first reflection surfaceof pressure wave M1 and the central axis of rotation of the paraboloidof revolution of the second reflection surface of pressure wave M2coincide with each other. In addition, the central axis of the deliverychannel pipe 51, the central axis of the displacement plane 71 of theactuator 70, and the central axes of rotation of the paraboloid ofrevolution of the first reflection surface of pressure wave M1 and theparaboloid of revolution of the second reflection surface of pressurewave M2 are nearly parallel to one another and are away from oneanother. Therefore, as shown in FIG. 5, the actuator 70 has a columnarshape having the displacement plane 71 and is located so as to be nearlyparallel to the central axes of rotation of the first reflection surfaceof pressure wave M1 and the second reflection surface of pressure waveM2.

Next, the propagation of a pressure wave in the fluid ejection device 10structured as described above will be described with reference to FIG.6.

FIG. 6 is an explanatory diagram showing the propagation of a pressurewave according to this embodiment. When the pressure chamber 60 isfilled with liquid, if the actuator 70 stretches rapidly (in thedirection of an arrow A1), a plane pressure wave is generated by thedisplacement plane 71, and the generated plane pressure wave propagatesto the first reflection surface of pressure wave M1 in a directionnearly parallel to the central axis of the displacement plane 71 (in thedirection of an arrow a1), and is reflected from the first reflectionsurface of pressure wave M1. After converging on the first focus F1, thereflected pressure wave spreads in the direction of the secondreflection surface of pressure wave M2 (in the direction of an arrow ofa2), and is reflected from the second reflection surface of pressurewave M2. Since the first focus F1 is a common focus of the paraboloid ofrevolution of the first reflection surface of pressure wave M1 and theparaboloid of revolution of the second reflection surface of pressurewave M2, the pressure wave reflected from the second reflection surfaceof pressure wave M2 propagates through the delivery channel 52 in thedirection of the central axis of the delivery channel pipe 51 (in thedirection of an arrow a3).

Therefore, according to this embodiment, the central axis of thedelivery channel pipe 51, the central axis of the displacement plane 71of the actuator 70, and the central axes of rotation of the paraboloidof revolution of the first reflection surface of pressure wave M1 andthe paraboloid of revolution of the second reflection surface ofpressure wave M2 are in a state in which they are offset. Thus, thepressure wave a2 reflected from the first reflection surface of pressurewave M1 propagates in a direction which is away from the displacementplane 71 in a planar direction, and enters the second reflection surfaceof pressure wave M2. The second reflection surface of pressure wave M2can reflect the pressure wave in nearly parallel to the plane pressurewave a1 generated by the actuator 70 and make the pressure wavepropagate through the delivery channel pipe 51 which is also located ina position nearly parallel to the central axis of the displacement plane71 and away therefrom. This makes it possible to increase configurationflexibility of the fluid ejection device 10 and transfer the pressurewave efficiently to the inside of the delivery channel pipe 51.

Fourth Embodiment

Next, a fluid ejection device according to a fourth embodiment will bedescribed with reference to the drawing. Unlike the third embodimentdescribed above (see FIG. 5), the features of the fourth embodiment arethat the second reflection surface of pressure wave M2 is formed as anellipsoid of revolution, and a second focus F2 located on the major axisof the ellipsoid of revolution exists inside the delivery channel pipe51. Therefore, only differences from the third embodiment are explained,and such elements as are found also in the third embodiment will beidentified with the same reference characters.

FIG. 7 is a sectional view showing the structure of the fluid ejectiondevice according to this embodiment and the propagation of a pressurewave. In FIG. 7, the first reflection surface of pressure wave M1 isformed as a paraboloid of revolution, and the second reflection surfaceof pressure wave M2 is formed as an ellipsoid of revolution. The centralaxis of rotation of the paraboloid of revolution of the first reflectionsurface of pressure wave M1 and the central axis of rotation of theellipsoid of revolution of the second reflection surface of pressurewave M2 coincide with each other. In addition, the central axis of thedelivery channel pipe 51, the central axis of the displacement plane 71of the actuator 70, the central axis of the paraboloid of revolution ofthe first reflection surface of pressure wave M1, and the central axisof rotation of the ellipsoid of revolution of the second reflectionsurface of pressure wave M2 are nearly parallel to one another and areaway from one another.

The focus of the paraboloid of revolution of the first reflectionsurface of pressure wave M1 is the same as one of the focuses of theellipsoid of revolution of the second reflection surface of pressurewave M2, and this common focus is referred to as a first focus F1. Inaddition, the ellipsoid of revolution of the second reflection surfaceof pressure wave M2 has a second focus F2 on the major axis thereof in aposition farther away from the ellipsoid of revolution of the secondreflection surface of pressure wave M2 than the first focus F1, and thesecond focus F2 is disposed inside the delivery channel pipe 51.

With this structure, when the actuator 70 stretches rapidly (in thedirection of an arrow A1), a plane pressure wave is generated by thedisplacement plane 71, and the generated plane pressure wave propagatesin the direction of the first reflection surface of pressure wave M1 (inthe direction of an arrow a1) and is reflected from the first reflectionsurface of pressure wave M1. After converging on the first focus F1, thereflected pressure wave spreads to the second reflection surface ofpressure wave M2 (in the direction of an arrow a2), enters the secondreflection surface of pressure wave M2, and is reflected therefrom.After converging on the second focus F2, the pressure wave reflectedfrom the second reflection surface of pressure wave M2 spreads, reachesthe inner wall of the delivery channel pipe 51, and propagates throughthe delivery channel 52 while being reflected from the inner wall (thepressure wave is shown by an arrow a4).

Since the second focus F2 is disposed in the delivery channel pipe 51(in the delivery channel 52), a pressure wave a3 propagates through thedelivery channel pipe 51. Therefore, the pressure wave a3 reflected fromthe second reflection surface of pressure wave M2 is made to converge inthe delivery channel pipe 51.

According to this embodiment, the second reflection surface of pressurewave M2 formed as an ellipsoid of revolution has the second focus F2 inthe delivery channel pipe 51. Therefore, the pressure wave which hasconverged on the second focus F2 propagates while being reflected fromthe inner wall of the delivery channel pipe 51. Also with such aconfiguration, it is possible to make the plane pressure wave generatedby the actuator 70 propagate through the delivery channel pipe 51efficiently.

Fifth Embodiment

Next, a fluid ejection device according to a fifth embodiment will bedescribed with reference to the drawings. Unlike the first embodimentdescribed above (see FIG. 1), in the fifth embodiment, the central axesof rotation of the paraboloid of revolution of the first reflectionsurface of pressure wave M1 and the paraboloid of revolution of thesecond reflection surface of pressure wave M2 are not parallel to eachother (however, there is a common point/a point of intersection of thesecentral axes, which is a focus only). In addition, the features of thefifth embodiment are that the central axis of the displacement plane 71of the actuator 70 and the central axis of rotation of the firstreflection surface of pressure wave M1 are nearly parallel to eachother, and the central axis of rotation of the second reflection surfaceof pressure wave M2 and the central axis of the delivery channel pipe 51are nearly parallel to each other. Therefore, only differences from thefirst embodiment are explained, and such elements as find theirfunctionally equivalent counterparts in the first embodiment will beidentified with the same reference characters.

FIG. 8 is a sectional view showing the structure of the fluid ejectiondevice according to this embodiment. In FIG. 8, the central axis ofrotation of the paraboloid of revolution of the first reflection surfaceof pressure wave M1 and the central axis of rotation of the paraboloidof revolution of the second reflection surface of pressure wave M2 arenot parallel to each other. In addition, the central axis of thedelivery channel pipe 51, the central axis which is nearly parallel tothe central axis of rotation of the second reflection surface ofpressure wave M2, and the central axis of the displacement plane 71 ofthe actuator 70, the central axis which is nearly parallel to thecentral axis of rotation of the first reflection surface of pressurewave M1, are displaced from each other. The actuator 70 has a columnarshape having the displacement plane 71, and is disposed so as to benearly parallel to the central axis of rotation of the first reflectionsurface of pressure wave M1.

Moreover, since the central axis of the delivery channel pipe 51 and thecentral axis of rotation of the paraboloid of revolution of the firstreflection surface of pressure wave M1 are displaced from each other,the delivery channel pipe 51 is provided so as to extend and be inclinedwith respect to a displacement direction of the actuator 70 (a directionof an arrow A).

Next, the propagation of a pressure wave in the fluid ejection device 10structured as described will be described with reference to FIG. 9.

FIG. 9 is an explanatory diagram showing the propagation of the pressurewave according to this embodiment. When the pressure chamber 60 isfilled with liquid, if the actuator 70 stretches rapidly (in thedirection of an arrow A1), a plane pressure wave is generated by thedisplacement plane 71, and the generated plane pressure wave propagatesin a vertical direction with respect to the displacement plane 71 to thefirst reflection surface of pressure wave M1 (in the direction of anarrow a1), and is reflected from the first reflection surface ofpressure wave M1. After converging on the first focus F1, the reflectedpressure wave spreads to the second reflection surface of pressure waveM2 (in the direction of an arrow a2), and is reflected from the secondreflection surface of pressure wave M2. Since the first focus F1 is acommon focus of the paraboloid of revolution of the first reflectionsurface of pressure wave M1 and the paraboloid of revolution of thesecond reflection surface of pressure wave M2 and the second reflectionsurface of pressure wave M2 is formed as a paraboloid of revolution, thepressure wave travels in a direction (in the direction of an arrow a3)inclined to the direction (the direction of the arrow a1) in which theplane pressure wave propagates. Since the delivery channel pipe 51 isprovided so as extend in the same direction as the direction in whichthe pressure wave travels, the pressure wave propagates through thedelivery channel pipe 51.

The pressure wave a3 reflected from the second reflection surface ofpressure wave M2 propagates in a direction inclined to the direction inwhich the plane pressure wave a1 generated by the actuator 70propagates. Thus, by making the central axis of the delivery channelpipe 51 coincide with the direction in which the pressure wave a3propagates, it is possible to realize a configuration of the fluidejection device 10 having the delivery channel pipe 51 in a position offthe central axis of the displacement plane 71 of the actuator 70 in anintended inclined direction and make the pressure wave generated by theactuator 70 propagate through the delivery channel pipe 51 efficiently.

Sixth Embodiment

Next, a fluid ejection device according to a sixth embodiment will bedescribed with reference to the drawing. Unlike the fifth embodimentdescribed above (see FIG. 8), the features of the sixth embodiment arethat the second reflection surface of pressure wave M2 is formed as anellipsoid of revolution, and a second focus F2 located on the major axisof the ellipsoid of revolution exists inside the delivery channel pipe51 (the delivery channel 52). Therefore, only differences from the fifthembodiment are explained, and such elements as are found also in thefifth embodiment will be identified with the same reference characters.

FIG. 10 is a sectional view showing the structure of the fluid ejectiondevice according to this embodiment and the propagation of a pressurewave. In FIG. 10, the first reflection surface of pressure wave M1 isformed as a paraboloid of revolution, and the second reflection surfaceof pressure wave M2 is formed as an ellipsoid of revolution. The centralaxis of rotation of the paraboloid of revolution of the first reflectionsurface of pressure wave M1 and the central axis of rotation of theellipsoid of revolution of the second reflection surface of pressurewave M2 are not parallel to each other (however, there is a commonpoint/a point of intersection of these central axes, which is a focusonly). In addition, the central axis of the displacement plane 71 of theactuator 70 and the central axis of rotation of the first reflectionsurface of pressure wave M1 are nearly parallel to each other, and thecentral axis of rotation of the second reflection surface of pressurewave M2 and the central axis of the delivery channel pipe 51 are nearlyparallel to each other.

The focus of the paraboloid of revolution of the first reflectionsurface of pressure wave M1 is the same as one of the focuses of theellipsoid of revolution of the second reflection surface of pressurewave M2, and this common focus is referred to as a first focus F1. Inaddition, the ellipsoid of revolution of the second reflection surfaceof pressure wave M2 has a second focus F2 on the major axis thereof, andthe second focus F2 is disposed inside the delivery channel pipe 51.

With this structure, when the actuator 70 stretches rapidly (in thedirection of an arrow A1), a plane pressure wave a1 is generated by thedisplacement plane 71, and the generated plane pressure wave a1propagates to the first reflection surface of pressure wave M1 and isreflected from the first reflection surface of pressure wave M1. Afterconverging on the first focus F1, the reflected pressure wave a2 spreadsto the second reflection surface of pressure wave M2, enters the secondreflection surface of pressure wave M2, and is reflected therefrom.After converging on the second focus F2, the pressure wave a3 reflectedfrom the second reflection surface of pressure wave M2 spreads, reachesthe inner wall of the delivery channel pipe 51, and propagates throughthe delivery channel 52 while being reflected from the inner wall (thisreflected pressure wave is shown as a pressure wave a4).

Since the second focus F2 is disposed in the delivery channel pipe 51(the delivery channel 52), the pressure wave a3 propagates through thedelivery channel pipe 51. Therefore, the pressure wave a3 reflected fromthe second reflection surface of pressure wave M2 is made to converge inthe delivery channel pipe 51.

The second reflection surface of pressure wave M2 has the second focusF2 in the delivery channel pipe 51. Therefore, the pressure wave whichhas converged on the second focus F2 propagates while being reflectedfrom the inner wall of the delivery channel pipe 51. This makes itpossible to make the pressure wave generated by the actuator 70propagate through the delivery channel pipe 51 efficiently.

Incidentally, the fluid ejection device 10 described above can beapplied to a unit of transporting and ejecting a minute amount of liquidsuch as ink or a chemical solution and can be applied to cleaning etc.of a tubule or a minute gap of a medical device, a living body, and anapparatus. As a typical example, cooling devices and medical deviceswill be described.

Cooling Devices

Cooling devices use the fluid ejection devices described in the first tosixth embodiments described above. These fluid ejection devices 10discharge a series of pulsed minuscule droplets at high velocity out ofthe fluid ejection opening (the nozzle) 53 by intermittently driving theactuator 70. Specifically, cooling by the ejection of pulsed minusculedroplets includes a cooling medium for cooling a heat source such as asolid light source and a cooling medium cooling unit cooling the coolingmedium whose temperature has been increased as a result of absorbing theamount of heat generated by the heat source. In addition, such a coolingdevice has an advantage that the cooling medium cooling unit is drivenfor the duration corresponding to the amount of heat generation of aheating element from the viewpoint of reducing noise during cooling andachieving power savings.

Medical Devices

Medical devices use the fluid ejection devices described in the first tosixth embodiments described above. These fluid ejection devices 10 ejecta series of pulsed minuscule droplets at high velocity out of the fluidejection opening (the nozzle) 53 by intermittently driving the actuator70. Operations conducted by using ejection of pulsed minuscule dropletshave excellent properties as operative procedures, such as causing nothermal damage when excising, incising, or crushing a living tissue andbeing capable of selectively excising and preserving a living tissue.Moreover, another advantage is that, when operations etc. are conductedby using such a fluid ejection device 10, the amount of ejected liquidis small as compared to an existing device using a high-pressure steadyflow, making it easy to see an operative site.

What is claimed is:
 1. A fluid ejection device for ejecting a fluid, the fluid ejection device comprising: a pressure chamber communicating with a fluid ejection opening; an actuator having a diaphragm that varies the volume of the pressure chamber; a first paraboloid surface within the pressure chamber facing the diaphragm of the actuator; and a second paraboloid surface within the pressure chamber facing the first paraboloid surface, wherein a position of the first paraboloid surface is different from a position of the second parabolid surface in a first direction perpendicular to a direction of displacement of the diaphragm.
 2. The fluid ejection device according to claim 1, wherein a central axis of rotation of the first paraboloid surface and a central axis of rotation of the second paraboloid surface are nearly parallel to each other.
 3. The fluid ejection device according to claim 2, wherein the central axis of rotation of the first paraboloid surface and the central axis of rotation of the second paraboloid surface coincide with each other.
 4. The fluid ejection device according to claim 1, wherein a central axis of rotation of the first paraboloid surface and a central axis of rotation of the second paraboloid surface are not parallel to each other.
 5. The fluid ejection device according to claim 1, wherein a central axis of diaphragm and a central axis of rotation of the first paraboloid surface are nearly parallel to each other.
 6. The fluid ejection device according to claim 5, wherein the central axis of the diaphragm and the central axis of rotation of the first paraboloid surface coincide with each other.
 7. A medical device including the fluid ejection device according to claim
 1. 8. A medical device including the fluid ejection device according to claim
 2. 9. A medical device including the fluid ejection device according to claim
 3. 10. A medical device including the fluid ejection device according to claim
 4. 11. A medical device including the fluid ejection device according to claim
 5. 